1. Field
Embodiments relate to scheduling transmissions in communication systems.
2. Related Art
A scheduler or scheduling function is provided in a base station controller in order to provide scheduling or management of system. In general, a scheduler selects a mobile for transmission at a given time instant, and adaptive modulation and coding allows selection of the appropriate transport format (modulation and coding) for the current channel conditions seen by the mobile.
Third and fourth generation wireless data communications systems, such as UMTS/HSPA CDMA-2000 standard systems, 1×-EV-DO, Long Term Evolution (LTE 3GPP 4G) WiMAX and WiFi, management of system resources is paramount. This is because properties of data differ significantly from properties of voice. For example, a data transmission, unlike a voice transmission, is not necessarily continuous and may be embodied as a burst transmission or an intermittent-type transmission between a base station and a mobile, for example. Accordingly, a base station in a third-generation system will attempt to manage a large pool of data users by assigning radio resources to each user for transmission. Typically this is done utilizing a prioritization scheme controlled by a scheduler in the base station controller.
Accordingly, the scheduler must be able to manage these large numbers of users without wasting radio resources of the communication system. This management function becomes even more important as a base station attempts to meet QoS (Quality of Service) requirements. QoS is a general term that may represent a number of different requirements. As a basic tenant, QoS is indicative of providing guaranteed performance (e.g., such as a minimum/maximum data throughput, a minimum delay requirement, a packet loss rate, and a packet download time, etc.) in a wireless communication system.
Quality of Service (QoS) differentiation in wireless data networks allows network operators to generate more revenue than is possible with best-effort scheduling policies. The promise of additional revenue is based on the willingness of end users (subscribers) to pay more for perceptible improvements in service (e.g., lower latency, higher throughput, or more predictable performance). In addition, revenue may also be increased by controlling churn via prioritization as the quality of experience over long periods of time is improved. QoS differentiation also enables deployment of new services (e.g., streaming audio/video, packet voice etc.) that cannot be provided with acceptable quality over best-effort scheduling policies or algorithms such as highest rate user first (HRUF)) scheduling, maximum carrier to interference ratio scheduling (Max C/I) and proportional fair (PF) scheduling, etc.
However, traffic generated by new application phones has raised exponentially while the vast majority of revenues in excess of prescribed postpaid plan tariffs, are reaped by the web platform service providers and their ad-networks. Worse, the revenue from real-time interactive communications such as voice has plummeted due to the commoditization of the voice service and changing demographics with newer generations preferring texting to voice communications.